Getting to the field
Defending the field

As you head north on 206, take a right through town, where two creepers will be waiting. Take 'em out if you want, but there's no salvage to be had in the individual scenarios, and they won't follow you.

At the end of the road is a steep ramp. Hit it at a moderate speed (between 70 and 85 mph, depending on the weight of your vehicle), and you'll make a nice, controlled jump onto the mesa. If you go too fast, you'll clear the mesa entirely and will be destroyed upon impact.